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EDM Searches in storage rings. July 5, 2012 Frank Rathmann Seminar on Precision Experiments in Storage Rings. Topics. Why EDMs? Search for EDMs using storage rings Two projects , at BNL and Jülich

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edm searches in storage rings

EDM Searches in storage rings

July 5, 2012 Frank Rathmann

Seminar on Precision Experiments in Storage Rings

topics
Topics
  • Why EDMs?
  • Search for EDMs usingstoragerings
  • Twoprojects, at BNL andJülich
  • Spin coherence time
  • First directmeasurement

Resonance Method with RF E(B)-fields

  • Polarimetry
  • Timeline ofprojects, cooperations, workshops
  • Summary

EDM Searches in storage rings

what caused the baryon asymmetry
Whatcausedthe Baryon asymmetry?

Carina Nebula: Largest-seen star-birth regions in the galaxy

Whathappenedtothe antimatter?

  • Sakharov (1967):Three conditions for baryogenesis
  • B number conservation violated sufficiently strongly
  • C and CP violated,B and anti-Bs with different rates
  • Evolution of universe outside thermal equilibrium

EDM Searches in storage rings

slide4

Electric Dipole Moments (EDMs)

Permanent EDMs violate parity P and time reversal symmetry T

Assuming CPT to hold,

combined symmetry CP violated as well.

EDMs arecandidatestosolvemysteryof matter-antimatter asymmetry

 mayexplainwhywearehere!

EDM Searches in storage rings

history of neutron edm limits
Historyofneutron EDM limits
  • Smith, Purcell, Ramsey PR 108, 120 (1957)
  • RAL-Sussex-ILL(dn 2.9 10-26ecm) PRL 97,131801 (2006)

Adoptedfrom K. Kirch

EDM Searches in storage rings

slide6

Limits for Electric Dipole Moments

EDM searches - onlyupperlimits, in (uptonow):

Hugeeffortsunderwaytoimprovelimits / find EDMs

SensitivitytoNEW PHYSICS beyondthe Standard Model

485. WE-Heraeus-Seminar (July 0406, 2011)

SearchforElectric Dipole Moments (EDMs) at Storage Rings http://www2.fz-juelich.de/ikp/edm/en/

EDM Searches in storage rings

slide7

Why also EDMs of protons and deuterons?

Proton anddeuteron EDM experimentsmayprovideone order highersensitivity.

In particularthedeuteronmayprovide a muchhighersensitivitythanprotons.

  • Consensus in the theoretical community:
  • Essential to perform EDM measurements on different targets with similar sensitivity:
  • unfold the underlying physics,
  • explain the baryogenesis.

EDM Searches in storage rings

slide8

Search for Electric Dipole Moments

NEW: EDM search in time developmentofspinin a storage ring:

“Freeze“ horizontal spinprecession; watch

fordevelopmentof a verticalcomponent!

EDM Searches in storage rings

slide9

Search for Electric Dipole Moments

NEW: EDM search in time developmentofspinin a storage ring:

“Freeze“ horizontal spinprecession; watch

fordevelopmentof a verticalcomponent!

A magicstorage ring forprotons (electrostatic), deuterons, …

Onemachinewithm

EDM Searches in storage rings

slide10

Twostorage ring projectsbeingpursued

Jülich, focus on deuterons, or a combinedmachine

BNL forprotons all electricmachine

CW and CCW propagatingbeams

(from A. Lehrach)

(fromR. Talman)

EDM Searches in storage rings

slide11

BNL Proposal

2 beamssimultaneouslyrotating in an all electricring (cw, ccw)

ApprovedBNL-Proposal

Submittedto DOEGoal forprotons

Circumference

Technological challenges !

  • Spin coherence time
  • Beam positioning
  • Continuouspolarimetry
  • E - fieldgradients

Carry out proofofprincipleexperiments (demonstrators) atCOSY

EDM Searches in storage rings

most recent richard talmans concept for a j lich all in one machine
Most recent: Richard Talmansconceptfor a Jülich all-in-onemachine

Iron-free, current-only, magnetic bending, eliminates hysteresis

B

A

Formoredetails, seeRichard‘slecture

B

A

EDM Searches in storage rings

the frozen spin method
The frozen spin Method

Fortransverseelectricandmagneticfields in a ring ( ),

anomalousspin precession isdescribedby

x

Magic condition: Spin alongmomentumvector

Foranysignof, in a combinedelectricandmagneticmachine

For(protons) in an all electric ring

(magic)

EDM Searches in storage rings

slide14

Magic condition: Protons

Case 1: fieldonly

EDM Searches in storage rings

slide15

Magic condition: Protons

Case 2: and fields

magicenergy

magicenergy

EDM Searches in storage rings

slide16

Magic condition: Deuterons

and fields

EDM Searches in storage rings

slide17

Magic condition: Helions

and fields

EDM Searches in storage rings

slide18

Parameters for Richard Talmans all-in-onemachine

Talman/Gebel givemaximumachievablefieldofcoppermagnetsof ~ 0.15 T.

  • Fitting such a machineintothe COSY buildingfavorslowermomenta.
  • Couldsomeoneplease check this!

EDM Searches in storage rings

edm at cosy cooler synchrotron
EDM at COSY –COolerSYnchrotron

Cooler andstorage ring for (polarized) protonsanddeuterons

Phase space

cooledinternal &

extractedbeams

COSY

… the spin-physics machine

for hadron physics

Injector cyclotron

EDM Searches in storage rings

edm at cosy cooler synchrotron1
EDM at COSY –COolerSYnchrotron

Cooler andstorage ring for (polarized) protonsanddeuterons

Phase space

cooledinternal &

extractedbeams

COSY

… an ideal starting point

for a srEDM search

Injector cyclotron

EDM Searches in storage rings

slide21

“spin closed orbit vector”

makes one turn

“spin tune”

if ║

ring

stable polarization

A

Spin closedorbit

one particle with

magnetic moment

EDM Searches in storage rings

spin coherence
Spin coherence

Weusuallydon‘tworryaboutcoherenceofspinsalong

Polarization not affected!

Atinjection all

spinvectorsaligned (coherent)

After some time, spinvectorsget out ofphaseandfullypopulatethecone

Situation very different, whenyou deal with

Longitudinal polarizationvanishes!

In an EDM machinewithfrozenspin, observation time is limited.

Atinjection all spinvectorsaligned

After some time, thespinvectorsare all out ofphaseand in the horizontal plane

EDM Searches in storage rings

estimate of spin coherence times n n nikolaev
Estimateofspincoherencetimes (N.N. Nikolaev)

Onesourceofspincoherencearerandomvariationsofthespin tune

due tothemomentumspread in the beam

and

israndomizedby e.g., electroncooling

Estimate:

Spin coherence time fordeuteronsmaybelarger thanforprotons

EDM Searches in storage rings

slide24

First measurementofspincoherence time

2011 Test measurementsat COSY

Polarimetry:

Spin coherence time:

decoherence

time

oscillation

capture

from Ed Stephenson

and Greta Guidoboni

EDM Searches in storage rings

topics1
Topics
  • Why EDMs?
  • Search for EDMs usingstoragerings
  • Twoprojects, at BNL andJülich
  • Spin coherence time
  • First directmeasurement

Resonance Method with RF E(B) –fields

  • Polarimetry
  • Timeline ofprojects, cooperations, workshops
  • Summary

EDM Searches in storage rings

slide26

ResonanceMethodwith RF E-fields

spin precession governedby:

(* restframe)

verticalpolarization

RF E-field

  • Two situations:
    •  EDM effect
    •  no EDM effect

stored d

Polarimeter (dpelastic)

  • This way, the EDM signalisaccumulatedduringthecycle.
  • Statistical improvementoversingle turn effectisabout: .
  • Brings us in therangefor.
  • But: Flippingfields will leadtocoherent betatron oscillations, withhardto handle systematics.

EDM Searches in storage rings

slide27

Simulation ofresonanceMethodwith RF E-fieldsfordeuteronsat COSY

Parameters: beam energy

assumed EDM

E-field

E-fieldreversedevery

Constant E-field

Numberofturns

Numberofturns

EDM Searches in storage rings

slide28

Simulation ofresonanceMethodwith RF E-fieldsfordeuteronsat COSY

Parameters: beam energy

assumed EDM

E-field

Linear extrapolationoffor a time periodof

EDM effectaccumulates

Polarimeter determines

Numberofturns

EDM Searches in storage rings

slide29

ResonanceMethodwith „magic“ RF Wien filter

Avoidscoherent betatron oscillationsof beam.

Radial RF-E andvertical RF-B fieldstoobservespinrotation due to EDM

Approach pursuedfor a firstdirectmeasurementat COSY.

 „Magic RF Wien Filter“ no Lorentz force

„Indirect“ EDM effect

Tiltofprecession plane due to EDM

RF E(B)-field

Observable:

Accumulationofverticalpolarizationduringspincoherence time

stored d

Transversepolarization

Polarimeter (dpelastic)

  • Statistical sensitivityfor in therange torangepossible.
  • Alignmentandfieldstabilityof ring magnets
  • Imperfectionof RF-E(B) flipper

EDM Searches in storage rings

operation of magic rf wien filter
Operation of „magic“ RF Wien filter

Radial E andvertical B fieldsoscillate, e.g., with(here).

beam energy

Spin coherence time maydepend on excitationand on chosenharmonics

(seeKolyaNikolaev‘slecture).

EDM Searches in storage rings

slide31

Simulation ofresonanceMethod

with „magic“ Wien filterfordeuteronsat COSY

Parameters: beam energy

assumed EDM

E-field

Linear extrapolationoffor a time periodof

Preliminary, based on K. Nikolaevsderivationofthecombinedrotationmatricesof E/B flipperand ring

EDM effectaccumulates in .

EDM Searches in storage rings

slide32

Simulation ofresonanceMethod

with „magic“ Wien filterfordeuteronsat COSY

Parameters: beam energy

assumed EDM

E-field

Linear extrapolationoffor a time periodof.

EDM effectaccumulates in

EDM Searches in storage rings

slide33

Simulation ofresonanceMethod

with Magic Wien filterfordeuteronsat COSY

Parameters: beam energy

assumed EDM

E-field

Linear extrapolationoffor a time periodof.

EDM effectaccumulates in

EDM Searches in storage rings

some polarimetry issues
Some polarimetry issues
  • srEDMexperimentsusefrozenspinmode, i.e., beam mostlypolarizedalongdirectionofmotion,
  • most promising ring optionsusecw & ccwbeams.
  • scattering on C destructive on beam andphase-space,
  • scatteringon C determinespolarizationofmainlyparticleswith large betatron amplitudes, and
  • is not capabletodetermine .
  • Forelasticscattering longitudinal analyzingpowersaretiny (violatesparity).

Ideally, use a methodthatwoulddetermine.

pCanddC polarimetry isthecurrentlyfavoredapproachforthepEDMexperimentat BNL

EDM Searches in storage rings

exploit observables that depend on beam and target polarization
Exploit observables thatdepend onbeam andtargetpolarization

Spin-dependent differential crosssectionfor

Analyzing power

Spin correlations

In scattering, necessary observables are well-knownin therangeMeV (not so foror).

EDM Searches in storage rings

how could one do that determine
How couldone do that, determine?

Detector

CW

CCW

cell

  • Detector determinesofcw & ccwbeamsseparately, based on kinematics.
  • Alignmentoftargetpolarization along axesbymagneticfields. Leads tounwanted MDM rotations absolute no-goin EDM experiments.

Suggestion 1: Use a polarizedstoragecelltarget

EDM Searches in storage rings

how could one do that determine1
How couldone do that, determine?

Detector

Polarizedionsource(~10 MeV)

  • Collidetwoexternalbeamswithcwandccwstoredbeams.
  • Energycouldbetunedtomatchdetectoracceptance.
  • Polarizationcomponentsofprobinglow-energy beam canbemadelarge, wouldbeselectedbyspinrotators in thetransmissionlines.
  • Luminosityestimatesnecessary(Andro, David, Jörg)

Suggestion 2: Usecolliding beam fromexternalsource

EDM Searches in storage rings

how could one do that determine2
How couldone do that, determine?

Detector

CW

CCW

  • Requiresluminosity, -functionsat IP shouldberathersmall.
  • Advantage oversuggestion 2. isthatsupportsluminosity.
  • Disadvantageisthatsensitivitycomesmainlyfromtermswithand.
  • Detailedestimatesnecessary (Andro, David, Jörg).

Suggestion 3: Usedirectlyreactionsfromcollidingbeams

EDM Searches in storage rings

luminosity estimate for the collider option
Luminosityestimateforthecollideroption

Conditions:

Even undertheseveryoptimisticassumptions, event rate will beratherlow.

EDM Searches in storage rings

topics2
Topics
  • Why EDMs?
  • Search for EDMs usingstoragerings
  • Twoprojects, at BNL andJülich
  • Spin coherence time
  • First directmeasurement

Resonance Method with RF E(B) –fields

  • Polarimetry
  • Timeline of projects, cooperations, workshops
  • Summary

EDM Searches in storage rings

slide41

TechnicallydriventimelineforpEDMat BNL

15

18

12

13

14

16

17

19

20

21

Two years R&D/preparation

One year final ring design

Two years ring/beam-line construction

Two years installation

One year “string test”

EDM Searches in storage rings

stepwise approach in the jedi project
Stepwiseapproach in the JEDI project

Time scale: Steps 1 and 2: < 5 years

Steps 3 and 4: > 5 years

EDM Searches in storage rings

slide43

srEDM cooperations

International srEDM Network

Institutional (MoU) and Personal (Spokespersons …) Cooperation, Coordination

srEDMCollaboration (BNL)

(spokespersonYannisSemertzidis)

JEDI Collaboration (FZJ)(spokespersons: A. Lehrach, J. Pretz, F.R.)

  • Common R&D
        • RHICEDM-at-COSY
    • Beam Position Monitors Polarimetry
    • (…) Spin Coherence Time
    • Cooling
  • Spin Tracking (…)

Study Group

First directmeasurement

Ring Design

DOE-Proposal(submitted)

CD0, 1, …

HGF Application(s)

pEDM Ring at BNL

JEDI

EDM Searches in storage rings

slide44

EDM Workshop at ECT* (Trento)

October 1-5, 2012

http://www.ectstar.eu/

EDM Searches in storage rings

slide45

Summary

  • Measurementsof EDMs areextremelydifficult, but thephysicsisfantastic!
  • Twostorage ring projects, at BNL and Jülich
  • All-in-onemachinewithcopper-onlymagnets
  • Pursuespincoherence time measurementsatCOSY
  • First directEDM measurementat COSY

Resonance Method with RF E(B) -fields

  • Polarimeter conceptstobeaddressedbysimulations
  • JEDI collaborationestablished

EDM Searches in storage rings

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